Abstract: A method of preparing a porous article is provided. The method includes: contacting a porous substrate with a first reactant that enters pores of the substrate; and contacting the porous substrate bearing the first reactant with a second reactant that is capable of reacting with the first reactant in an interfacial polymerization reaction; the amounts of first and second reactant being selected such that there occurs no, or substantially no, closing of pores of the substrate by the formed polymer. The invention also provides a porous article bearing a compound which is photochemically reactive and capable of undergoing a substantially non-reversible chemical transformation upon exposure to ultra-violet, visible or near infra-red irradiation. The photochemically reactive compound can be derivatized by irradiation and further reaction to provide a wide variety of useful membranes, for example, for microfiltration or for biochemical reactions and separations.